[patch 13/24] KVM: s390: prepare for hugepage vmalloc

From: Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: KVM: s390: prepare for hugepage vmalloc

The Create Secure Configuration Ultravisor Call does not support using
large pages for the virtual memory area.  This is a hardware limitation.

This patch replaces the vzalloc call with an almost equivalent call to the
newly introduced vmalloc_no_huge function, which guarantees that only
small pages will be used for the backing.

The new call will not clear the allocated memory, but that has never been
an actual requirement.

Link: https://lkml.kernel.org/r/20210614132357.10202-3-imbrenda@linux.ibm.com
Fixes: 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") 
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Christian Borntraeger <redacted>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: David Hildenbrand <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/s390/kvm/pv.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/arch/s390/kvm/pv.c~kvm-s390-prepare-for-hugepage-vmalloc
+++ a/arch/s390/kvm/pv.c

@@ -140,7 +140,12 @@ static int kvm_s390_pv_alloc_vm(struct k
 	/* Allocate variable storage */
 	vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
 	vlen += uv_info.guest_virt_base_stor_len;
-	kvm->arch.pv.stor_var = vzalloc(vlen);
+	/*
+	 * The Create Secure Configuration Ultravisor Call does not support
+	 * using large pages for the virtual memory area.
+	 * This is a hardware limitation.
+	 */
+	kvm->arch.pv.stor_var = vmalloc_no_huge(vlen);
 	if (!kvm->arch.pv.stor_var)
 		goto out_err;
 	return 0;

_